These studies are designed to evaluate the clinical benefits achieved by iron chelation in patients with chronic iron overload. Detailed assessment of cardiac, endocrine and hepatic function are performed prior to initiation of chelation therapy and these analyses are repeated annually during the course of iron removal. Desferrioxamine is administered by subcutaneous infusion and the amount of iron removed is determined by quantitation of urinary iron excretion and careful recording of total iron administered by transfusion. Those patients who have no evidence of cardiac disease are randomized to receive either ascorbic acid (3 mg/kg) or placebo. Cardiac function is assessed by 24 hour recordings of the cardiac rhythm, echocardiography, and radionuclide cineangiography as well as standard clinical techniques. Radionuclide cineangiography during exercise provides a very sensitive index of cardiac function in that 13 of 16 patients who received over 100 units of blood failed to increase their ejection fraction during exercise in the normal fashion.